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Resolving observations of channel change into separate planimetric measurements of flood-plain formation and destruction reveals distinct relations between these processes and the flow regime. We analyzed a time sequence of eight sets of aerial imagery from 1939 to 2003 along the Little Missouri River, North Dakota, to relate flood-plain change to flow along this largely unregulated river (Miller and Friedman 2009). At the decadal scale flood-plain formation and destruction varied independently. Destruction was strongly positively correlated to the magnitude of infrequent high flows recurring every 5-10 years, while flood-plain formation was negatively correlated to the magnitude of frequent low flows exceeded 80% of the time. At the century scale, however, a climatically induced decrease in peak flows has reduced the destruction rate, limiting the area made available for flood-plain formation. The rate of destruction was not uniform across the flood plain. Younger surfaces were consistently destroyed at a higher rate than older surfaces, suggesting that throughput of contaminants would occur more rapidly than predicted by models that assume uniform residence time of sediment across the flood plain. Flood-plain age maps produced by analysis of sequential flood-plain images were similar to forest-age maps produced through dendrochronology, confirming the assumption of dendrogeomorphic studies that riparian tree establishment in this system is limited to recent channel locations.

The data archive contains the aerial photographs and channel delineations used in our analysis. The aerial photographs are in seven ZIP files arranged by photograph date: 1939, 1949, 1958, 1966, 1974, 1982 and 1995. The ZIP file you have downloaded contains the photographs for 1966. The images have been geo-referenced to the 1995 digital orthophoto quarter quadrangles as described by Miller and Friedman (2009). The separate images for each year can be viewed as a composite along with that year’s channel delineation using a geographic information system (GIS) such as ArcGIS. The 2003 IKONOS satellite imagery is proprietary and, therefore, cannot be served here. The channel delineations for all photo years (including 2003) and the delineation of the outer flood-plain boundary are stored as shapefiles within a separate ZIP file. These shapefiles can be manipulated with a GIS to reproduce the spatial analyses reported in Miller and Friedman (2009). Flow data beginning on October 1, 1934 are available for the US Geological Survey gage 06337000, Little Missouri River near Watford City, North Dakota, available at http://waterdata.usgs.gov/nwis.